Laboratory evaluation of the effect of Khaya senegalensis and Cassia occidentalis ethanolic leaves extracts against worker termites (Isoptera: Rhinotermitidoe) on treated wood sample

Abstract

Khaya senegalensis and Cassia occidentalis ethanolic leaves extract were evaluated for their effectiveness to suppress wood damage by termite at the Department of Biological Sciences, Bayero University, Kano, Nigeria. K. senegalensis was collected from Nana hall female hostel, old campus of Bayero University Kano, and C. occidentalis was collected from wild areas of Aminu Kano Teaching Hospital Zaria Road, Kano. Both plants were identified at the herbarium of the Department of Biological Sciences. The leaves were extracted using Soxhlets extraction method. Termite was collected at Bayero University quarters, new site and identified using taxonomic key. Wood sample used for the bioassay were collected from a carpenter shop at Tarauni Local Government Kano and was disinfested by drying in an oven at 60°C overnight. Bioassay was conducted in plastic containers. Extracts from these plants were separately prepared into different concentration (0.5, 1.0 and 1.5 g) and inoculated into separate plastic containers containing 20 g of disinfested wood sample which correspond to 2.5, 5.0 and 7.5% w/w, respectively. Forty (40) workers termite were introduced into these containers separately. Control treatment was set along. Each treatment was replicated three times; mortality of the insect was assessed after 24 h interval. This study indicated that both C. occidentalis and K. senegalensis ethanolic extracts at varying level of application recorded mortality of the workers termite within the shortest duration of application when compared with the untreated wood. 100% mortality of workers termite was observed on wood treated with C. occidentalis extract at all level of application after 120 h of treatment while 100% mortality of the workers termite was recorded on wood treated with K. senegalensis at all level of application after 240 h of treatment. This indicated that extract of C. occidentalis was more effective than the extract of K. senegalensis in killing workers termite on wood treated with the extract. Key words: Cassia occidentalic, Khaya senegalensis, workers termite, ethanolic leaf extract.